Quote from Apple support
Add a device to the list
After you sign in on a device with your Apple ID, that device appears in the list. Here's where you need to sign in:
- For iOS 9, sign in to iCloud, iMessage, FaceTime, the iTunes and App Store, or Game Center on the device. You can also see your paired Apple Watch.
- For iOS 8 sign in to iCloud or the iTunes and App Store on the device. You can also see your paired Apple Watch.
- For OS X Yosemite and later or Windows 10 and later, sign in to iCloud on the device.
- For tvOS 7 or later, sign in to the iTunes and App Store on the device.
- If any of your devices are using earlier versions of iOS, OS X, or tvOS, you won’t see them in your device list.
iMac (27-inch, Late 2013), OS X El Capitan (10.11.4)
